This si the time that scripts in that area fire. You could try selectively removing them and seeing if that makes a difference. Also you can use webmin to look at all of the cron jobs and see if there is a problem there. Is there nothing in your log files? What version of TB are you using? 2.2x or 2.3Beta
Unfortunately, I’ve found that amportal does not wait for asterisk to terminate before it tries to restart - therefore it issues the restart too early.